Other children treated on the wards and now discharged from Guy's Hospital in London may be carriers, and angry parents yesterday criticised officials for not warning them of the dangers.
An intensive care unit at the hospital has been closed to new admissions since last week, after an outbreak of Klebsiella which is resistant to most antibiotics. The bacteria can lead to pneumonia, blood poisoning and in rare cases, meningitis, in sick children. A second intensive care unit eight floors away, for children who have had heart surgery, was also affected. It remains open but is now being screened and cleaned. Three other wards are also being cleaned, and non-urgent heart surgery for children has been halted.
Microbiologists said last night that poor hygiene - hand-to-hand contact - was an important mode of transmission of Klebsiella. The resistance of the Guy's strain to antibiotics also suggested that it had arisen in the hospital.
Dr Geoff Scott, a consultant microbiologist at University College Hospital and spokesman for the Hospital Infection Society, said nurses tended to work on a single ward, so a doctor working between two wards was the most likely vector. Dr David Wright, a microbiologist at Charing Cross Hospital, said the bacteria may then have been transferred between patients on the hands or gloves of doctors and nurses. 'The bacteria occurs quite naturally in the stomach but if it gets outside, it lives in moisture on the skin and is spread by contact.'
But Dr Donal O'Sullivan, a consultant in communicable disease control for Lewisham and North Southwark Health Authority, said there was no evidence to suggest that sloppy procedures were to blame. 'This is a common problem in high technology or intensive care units where there are very ill children and powerful antibiotics are used, allowing the emergence of resistant strains of infection.
'We have intensified measures to prevent transmission of the organism. There is no suggestion it was more likely to be transmitted because of the failure to carry out effective procedures. Nothing more could have been done in my opinion.' Staff were still being screened but no carriers had been found so far, he said.
The bacteria was first identified in a child on 15 July, but concern grew when another child found to be infected, died on 23 July. Caleb Ward was not closed until 30 July.
The children who died were under three months of age and had undergone major heart surgery. Klebsiella is mentioned on one child's death certificate as being a contributory factor, but Dr O'Sullivan said he did not know what was the stated cause of death of the other child.
Six other children, who range in age from birth to seven, are being cared for on the closed ward. Tests have shown they are carriers but none have symptoms of the infection.
One other child has been discharged and two youngsters who were infected are now clear, but remain in hospital for other medical reasons.
The parents of one dead baby said yesterday they were not told of the infection. Dean Bunn, aged two weeks, died after an operation to correct two holes in his heart. Trevor Bunn, the baby's father, told ITN: 'I don't know why they didn't tell us because they were giving us the bottom line all the way through because we knew he was seriously ill.' His wife, Lesley, said: 'They should tell every parent what is going wrong, not keep it silent.'
Dr O'Sullivan said other children discharged from Caleb and Russell Brock wards may be symptomless carriers but the hospital is not attempting to trace them. The bacteria would present no problem if the children were well and had healthy immune systems, he said. If they developed symptoms they would be admitted to hospital anyway.
But Jevan Amed, 46, whose daughter Melissa, 3, is in intensive care, said: 'The first I knew about it was in the newspaper report today. I am very concerned for my daughter's welfare at the moment and could do without this. All it would take is for the doctor to say everything's OK.'
Klebsiella is a common environmental bacterium and rarely causes health problems. George Haycock, professor of paediatrics at Guy's, said yesterday: 'We have made no attempt to disguise the presence of this organism. It might have been a contributory factor but these children were desperately ill.'
Infections arising within hospitals cost the NHS more than pounds 100m annually to investigate, treat and eradicate. More than one in ten surgical patients pick up an infection in hospital. Dr Geoff Scott said many doctors and nurses ignored basic hygiene rules such as washing their hands between patients. 'It has been shown time and time again that the greatest potential risk is on the hands of carers. It is all to do with habit.'Reuse content